GILDAS works in the LSR velocity frame and has limited
polarization capabilities (
IMAGER can only process
one polarization state at a time, see Section 15 for
details). Thus the casagildas() -
fits_to_uvt
sequence makes several assumptions:
- FDM (Frequency Division Mode) spectral windows are converted to
LSR frame using the mstransform tool
- TDM (Time Division Mode) spectral windows, which have low
spectral resolution (15 MHz), are assumed to be pure continuum
data, and remain in the default frame of the original measurement
set.
- The conversion from UVFITS to uv tables assumes that the data
is unpolarized5, and merges the initial polarization
states in an optimal way from the signal to noise point of view (i.e.
using the respective weights of the two parallel hand states).
- casagildas() takes the same input parameters
as the listobs() facility. Source and/or spectral
window selection can thus be made by the user at this stage
- casagildas() takes the same input parameters
as the mstransform() facility. Time integration
may be done at this stage, but this may limit the performance
of self-calibration at a later stage.
